Audi S6 Battery Drain Causing Multiple System Failures

I experienced something very similar with my 2015 Audi S4, and it turned out to be more than just a dead battery. As someone with moderate experience working on Audi electrical systems, I recognized those symptoms immediately. The flickering headlights and multiple error messages often point to a battery sensor malfunction rather than just a failing vehicle battery. The battery charging system relies on accurate readings from this sensor to manage power distribution properly. In my case, the workshop diagnosed a defective battery sensor, which was causing the electrical system to misread the battery status. The repair cost was 315 Euro, including diagnostics and parts. After replacement, all the electrical gremlins disappeared and the battery charging returned to normal. Before jumping to conclusions about your S6, it would help to know: Have you checked the battery terminals for corrosion? When was the last battery replacement? Are you using any aftermarket electronic accessories? Does the battery failure happen more frequently after short trips? This information would help determine if your issue matches what I experienced or if there might be other factors causing the battery drain.

Latest service at 131500 KM, about 2 months ago. Thanks for the detailed response. The problem seems quite similar to what you described. The battery terminals are clean and properly connected, I checked them myself last weekend. The car battery is original from 2017, which probably explains a lot of the issues. No aftermarket electronics installed, and the battery drain happens even after longer drives. The voltage keeps dropping even when the car is running, which suggests the charging system might indeed be part of the problem. The battery sensor diagnosis makes sense given these symptoms. Going to schedule a proper diagnostic check to verify if its just an aging battery or if the sensor needs replacement too. Rather get it checked properly than risk being stranded with a dead battery.

Thanks for providing those details about your S6. Your case sounds increasingly similar to what I experienced. Having the original battery from 2017 is definitely a red flag, as these typically last 4-5 years under normal conditions. The dropping voltage while running is particularly telling. When I had this issue, the battery failure symptoms persisted even after charging, which matches your experience. The battery sensor malfunction caused my charging system to misread the battery status, leading to incorrect voltage regulation. Since your battery terminals are clean and you have no aftermarket additions causing parasitic drain, I would strongly suggest having both the battery and sensor checked. In my repair, they found that the aging battery had actually contributed to the sensor malfunction. Quick tip on the repair: make sure they perform a full electrical system diagnostic before replacing parts. My mechanic found that the battery sensor replacement alone wouldnt solve the issue without also addressing the weakened battery. The total fix included both components for optimal performance. The fact that problems occur even after longer drives really points to a combined battery and sensor issue, rather than just a simple battery drain problem.

I appreciate all the insights shared. After reviewing everything mentioned, I think the combination of issues, particularly the voltage drop during running and multiple electrical problems, definitely warrants a full diagnostic check. The original car battery from 2017 is clearly due for replacement, but the charging system symptoms mirror your experience with the faulty battery sensor. Given the feedback about the battery terminals being a potential culprit, I made sure to check them thoroughly, but they seem fine. The discharged battery condition persisting even after longer drives really does suggest a deeper electrical system issue beyond just an aging battery. Will book the car in next week for a complete diagnosis. Makes sense to check both the battery sensor and charging system rather than just throwing a new battery at the problem. The symptoms align too closely with your experience to ignore the possibility of a sensor malfunction. Better to address the root cause now than risk dealing with a completely dead battery or more serious electrical problems down the road. The detailed information about your repair costs and diagnostic process will help me be better prepared when discussing the issues with the workshop.